(a) Field of the Invention
The present invention relates to a thin film transistor, a thin film transistor display panel, and a manufacturing method thereof, and more particularly to a thin film transistor having crystalline silicon, a thin film transistor display panel having the thin film transistor, and a manufacturing method thereof.
(b) Description of the Related Art
In general, a thin film transistor (TFT) is used as a switching device for independently driving pixels in a flat display apparatus such as a liquid crystal display (LCD) apparatus and an organic light emitting display (OLED) apparatus. A thin film transistor display panel includes the thin film transistors, pixel electrodes connected to the thin film transistors, scan signal lines (or gate lines) for transmitting scan signals to the thin film transistors, and data lines for transmitting data signals.
Each of the thin film transistors includes a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode connected to the pixel electrode, and a semiconductor disposed on the gate electrode between the source and drain electrodes. The thin film transistors transmit the data signals from the data lines to the pixel electrodes according to the scan signals from the gate lines. Here, the semiconductor of the thin film transistor is made of polysilicon or amorphous silicon.
In general, silicon is classified as amorphous silicon and polysilicon according to the crystalline state thereof. Since the amorphous silicon can be deposited at a low temperature to form a thin film, the amorphous silicon is mainly used for a display apparatus in which a glass having a low melting point is used as a substrate. However, in comparison to the crystalline silicon, due to a low field effect mobility of the amorphous silicon, it is difficult to implement a Chip-In-Glass by directly designing and forming a driving circuit on a panel for the display apparatus. Therefore, production cost thereof increases.
On the other hand, although the polysilicon has better field effect mobility than the amorphous silicon, a process for forming the polysilicon is very complicated.